Many owners of passenger cars or estate cars employ a roof-rack, either to permit the carrying of a load which will not fit within the main body of the vehicle, on account of the physical dimensions of that load, or to increase the overall load-carrying capacity, when the available space within the body of the vehicle has already been filled. In either case, a load carried on a roof-rack is exposed to the elements, unless that load is covered by a tarpaulin, plastic sheet or the like. However, it can be difficult to securely tie-down such a cover, to prevent the cover flapping or filling with air when the vehicle is under way, for a number of reasons. For example, the load itself must be tied down securely to the roof-rack, and the ropes or cords used to do this may then inhibit the fitting of a cover closely over the load. On the other hand, if the cover is first placed over the load, the presence of the cover may inhibit the secure tying-down of the load, and moreover it may not be possible adequately to tension the cover, on account of interference between the cover and the ropes or cords tying down the load.
Another difficulty associated with the use of a cover over a load carried on a roof-rack is that if the cover is sufficiently large to extend over the largest load that is likely to be carried, then it will be much too big for a relatively small load. In such a case, the excess material of the cover must be made fast--but again, this can be relatively difficult to achieve in such a way that it will not flap or billow, when the vehicle is underway. Also, when the cover is not in use, it must be stowed within the vehicle, taking up space.